Many manufacturing applications require hole drilling to form holes in a target product. Mechanical drilling systems are appropriate for forming relatively large holes, but are not suitable for drilling small diameter holes because mechanical drilling methods are unable to drill small holes cleanly within tight tolerances.
Laser systems have been used in hole drilling systems because they can be precisely focused and can drill even small diameter holes relatively cleanly. However, these processes are thermal processes and often cause metallurgical damage in the holes they drill, leaving recast material on the sides of the hole walls that are prone to cracking and failure if highly stressed.
U.S. Pat. No. 5,184,434 to Hollinger et al. (“the '434 patent”) illustrates a cutting process using a small diameter jet of high pressure fluid containing abrasive particles to cut a target product. The '434 patent teaches fully wetting the abrasive in the fluid and also teaches treating the abrasive/fluid mixture to prevent the abrasive from settling out of the fluid. By controlling the size of the orifice through which the jet is output, the kerf width of the cut formed by the jet can be quite narrow, allowing the jet to make very fine cuts. However, the '434 patent focuses solely using the jet in a cutting process and does not address the special concerns of hole drilling in any way. As a result, currently known hole drilling systems still rely on mechanical or thermal processes or use a conventional abrasive waterjet hole drilling method using a high pressure waterjet orifice, a mixing chamber to entrain dry abrasive particles, and a focusing tube. The large physical dimensions of conventional waterjet system components severely limits the ability to drill holes in confined spaces and/or in closely-spaced hole patterns.
There is a desire for an improved hole drilling system and method that can drill holes in a target cleanly in closely-spaced patterns, with no thermal damage to the target, simultaneously and in non line-of-sight locations.